In utero sonography of genitourinary anomalies

Prenatal detection of congenital renal malformations by fetal ultrasonographic examination: an analysis of 709,030 births in 12 European countries

The study was performed to evaluate the prevalence of prenatal ultrasound diagnoses for renal anomalies in 20 registries of 12 European countries, and to compare the different prenatal scanning policies. Standardized data were acquired from 709,030 livebirths, stillbirths, and induced abortions during the study period of 2.5 years and transmitted for central analysis. At least one renal malformation was diagnosed in 1130 infants and fetuses. Prenatal diagnosis (PD) was given in 81.8% of all cases, 29% of these pregnancies were terminated. The highest detection rate was reported for unilateral multicystic dysplastic kidneys with 97% (102/105). An early diagnosis was documented for exstrophy of bladder at a mean gestational age of 18.5 weeks. Dilatations of the upper urinary tract were seen late in pregnancy at 28.3 weeks. Terminations of pregnancies (TOP) were performed in 67% (58/86) of the detected bilateral renal agenesis/dysgenesis, but only 4% of the unilateral multicystic dysplastic renal malformations (4/102). In about 1/3 of the cases, renal malformations are within the category of associated malformations, which include multiple non-syndromal malformations, chromosomal aberrations, and non-chromosomal syndromes. Renal malformations were detected in 2/3 of the associated category by the first prenatal ultrasound scan. Detection rates vary in the different countries of the European community due to diverse policies, ethical, and religious background. Countries with no routine ultrasound show the lowest rates in detection, and termination of pregnancy. Prenatally detected renal malformations should result in a careful examination for further anomalies. Prenatal ultrasound fulfills the needs of screening examinations and is a good tool in detecting lethal and severe renal malformations.

Prenatal bladder outlet obstruction secondary to ureterocele

We present 2 cases of prenatal hydroureteronephrosis and bladder outlet obstruction due to an obstructing ureterocele. Both neonates were stabilized and managed with early endoscopic decompression. Neither infant demonstrated significant function in the kidney ipsilateral to the ureterocele either before or after ureterocele puncture. There have been few cases reported of prenatal bladder outlet obstruction due to a ureterocele. Our limited experience has been poor with regard to salvaging the affected upper tract. Future definitive management will be tailored as more of these cases are documented.

Renal growth characteristics in children born with multicystic dysplastic kidneys

OBJECTIVES

To report on the growth characteristics of the affected and contralateral kidneys in children born with multicystic dysplastic kidneys (MCDKs).

METHODS

Thirty-three patients were enrolled from 1970 to 1995: 23 were initially managed nonoperatively (mean follow-up 3.39 years), and 10 underwent nephrectomy. Patients underwent radionuclide renal imaging and contrast voiding cystography. Serial ultrasonography was used to obtain measurements of the affected and contralateral kidneys. Blood pressure measurements and serum creatinine levels were available in some patients.

RESULTS

Among the 23 nonoperative patients, the affected MCDK involuted in 4 patients during a mean follow-up of 4.5 years at a rate of 1.02 cm/yr (24% annually); 7 kidneys decreased in size at a mean rate of 0.38 cm/yr (5.8% annually); 6 grew at a mean rate of 1.16 cm/yr (9.9% annually); 1 kidney did not change in size; and 5 children were lost to follow-up. The mean size of the contralateral kidneys at birth was 5.3 cm, 2 standard deviations larger than normal. Over time, this relative hypertrophy was maintained at a growth rate of 0.89 cm/yr (18.5% annually). Two patients who had undergone nephrectomy also had serial postoperative ultrasonic renal measurements, and contralateral growth was 0.61 cm/yr (12.16% annually). All but 1 patient had normal blood pressure measurements and serum creatinine levels.

CONCLUSIONS

Most MCDKs involute or decrease in size over time, although this may take many years. Contralateral hypertrophy is seen at birth and is maintained during childhood growth, regardless of whether the affected kidney is removed. There is no associated hypertension or malignancy when the dysplastic kidney is left in place.

Fetal renal growth evaluated by prenatal ultrasound examination

OBJECTIVE

To determine reference ranges for normal fetal renal size in a population of pregnant patients at Mayo Clinic Rochester.

DESIGN

Normal fetal kidneys were prospectively analyzed relative to gestational age and to fetal body weight.

MATERIAL AND METHODS

In 100 pregnant women, prenatal ultrasound examinations were performed between 18 and 39 weeks of gestation. Fetal renal length and volume were determined by prenatal ultrasonography and compared with gestational age and estimated fetal body weight. Reference ranges as a function of gestational age were obtained for fetal body weight, renal length, renal volume, renal length/ body weight, and renal volume/body weight. Reference ranges as a function of body weight were determined for renal length and renal volume. Polynomial least-squares regression analysis was used to model each of the growth variables (Y) as a function of either gestational age or body weight (X).

RESULTS

Graphic representation of these relationships are presented. These graphs include the 2.5, 5.0, 95.0, and 97.5 percentiles and the predicted value of Y from the regression equations. Fetal body weight, renal length, and renal volume increased throughout gestation, and the ratio between fetal renal volume and body weight remained constant.

CONCLUSION

These data about normal fetal renal growth relative to gestational age and fetal body weight should help identify fetal abnormalities in renal size or growth patterns.

Hydronephrosis in the neonate and young infant: current concepts

Asymptomatic neonates with urological abnormalities that were discovered antenatally or during screening sonography in the neonatal period differ in a number of important ways from those presenting later with overt clinical signs and symptoms of urological disease. The accumulated experience with these neonates over the past decade has led to important advances in our understanding of the epidemiology, diagnosis, and management of congenital disorders of the urinary tract.

Biochemical diagnosis in prenatal uropathy

Thirty-two fetuses, six with prune-belly syndrome, seven with renal cyst, 19 with obstructive uropathy, underwent intrauterine fluid aspiration during weeks 15-37 of gestation. Fluid samples were analysed for Na, K, creatinine, urea, alpha 1-, and beta 2-microglobulin. Aspirate concentrations of sodium below 130 mmol/L and creatinine above 115 mumol/L indicate an active kidney and exclude a renal cyst. However, aspirates from fetal cysts or fetuses with obstructive uropathy showed analyte concentrations for sodium, potassium, creatinine, and urea corresponding to extracellular fluid (ECF). In conclusion fluid aspirates of fetuses with ultrasonographically detectable cystic cavities in the abdomen should be examined for sodium and creatinine to assess remaining renal function for planning of obstetric management.